1. Field of the Invention
This invention relates to improvements in a body mounting structure of an automotive vehicle, and more particularly to a device for suppressing a relative displacement between a vehicle frame and a vehicle body, used in the body mounting structure.
2. Description of the Prior Art
Hitherto a variety of body mounting structures of an automotive vehicle have been proposed and put into practical use. A typical one of them is disclosed in Japanese Utility Model Provisional Publication No. 61-158573 described as follows. The vehicle frame includes a pair of frame members which are located generally parallel and extend in a fore-and-aft direction of the vehicle. Each frame member is provided with several mount brackets for the vehicle body including a floor panel. Upper and lower insulators are securely disposed respectively on and below each mount bracket. A bolt is disposed vertically passing through the mount bracket and the insulators to securely connect them as a single unit. The floor panel is mounted on each upper insulator and fixed there by the bolt. Thus, the floor panel is elastically supported on the frame members through the insulators and the mount bracket. Accordingly, a force input during a bounce of the vehicle can be absorbed by the upper insulator whereas a force input during rebound of the vehicle can be absorbed by the lower insulator. Additionally, the vertical bolt can restrict a relative displacement in the fore-and-aft direction made between the vehicle frame and the floor panel during an abrupt vehicle starting, an abrupt vehicle braking, an abrupt vehicle turning, or the like.
However, difficulties have been encountered in this conventional body mounting structure. The vertical bolt can restrict to some extent the relative displacement between the vehicle frame and the floor panel; however, the vertical bolt is fixed only at an intermediate point corresponding to the mount bracket so that any displacement restriction is made to the lower end section of the bolt. Accordingly, when a large force input is made to either one of the vehicle frame (or the mount bracket) and the floor panel, the bolt is rotationally inclined around the above-mentioned intermediate point thereby providing the possibility of increasing a relative displacement amount between the floor panel and the vehicle frame. In order to prevent the relative displacement from increasing, the rigidity of the whole body mounting structure is raised by providing a variety of reinforcing members for the mount bracket and/or to the insulators. However, this affects the inherent input force absorbing ability of the insulators.